To understand the psychosocial and therapeutic concomitants of detoxification. Of particular interest is how these are manifest in two types of methadone clinics. Emphasis is placed on the patient's background at the time of induction to treatment, dosage during treatment and the goals of treatment. To understand the ramifications of maintaining abstinence. Especially to understand the mechanisms the individual uses to cope with opiate abstinence, e.g. substitution of a more constructive role function or of other addictions and the conditions conducive to the evolution of the various alternatives. The study will involve psychological testing in a repeated measures design and a comparison of the intake and follow-up status of patients who are gradually detoxified and have attained abstinence. Statistical analysis will be geared at producing weighted personal and treatment variables that are predictive of success at detoxifying and maintaining abstinence.